The present invention teaches enhancing fabrication yield of image sensors by using circuitry which compensates for faulty image sensor areas.
Consumer requirements have required larger and larger sensor arrays. However, as a sensor array gets larger, it becomes more difficult to reliably fabricate the sensor array. Fabrication yield and sensor cost can be proportional to the size of the sensor array.
Typically, any bad portion in a sensor array requires that the sensor array be discarded or used for another purpose. However, there have been attempts to incorporate circuitry which compensates for fabrication errors.
Such errors can be corrected using a median of a neighborhood surrounding the faulty pixel.
The median also has other applications which are well known in the art.
The present disclosure describes performing the median function over a pixel neighborhood. The result of that median function can be used to simulate an effect which is perceived by the user. According to the present system, on-chip processing is used to hardware-calculate the median function.
A number of different embodiments are described to use hardware to calculate the median function. That hardware is preferably on the same chip as the image sensor. Most preferably, this uses active pixel sensors, in which some circuitry is integrated onto the substrate along with the photosensor.